Remove Universal Analytics (UA) registration code

[chalin]

• Followup to Migrate to Google Analytics 4 (GA4) #245, which setup GA4
• Once the UA tag (UA-58468480-3) is no longer needed or is no longer receiving data (which will happen in 2023), the tag registration code should be removed from the website:
  

  website/layouts/default.html

  Lines 58 to 67 in 0cf826e

  	<!-- Google Analytics -->
  	<script>
  	(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
  	(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
  	m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
  	})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
  	ga('create', 'UA-58468480-3', 'auto');
  	ga('send', 'pageview');
  	</script>

[RichiH]

@chalin thanks. Will you update this issue / create a PR once this is the case?